sceibnee



(No Model.) 2 Sheets-Sheet 2.

o. E. SGRIBNBR. TELEPHONE EXCHANGE APPARATUS.

No. 442,144. Patented Dec. 9, 1890.

me Nonms swans co., Puo'rmumo., wnsnmarow n c NrTn TaTns PATENT CFFICE. Y

CHARLES` E. SCRIBIER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE VESTERN ELECTRIC COHPANY, CF SAME PLACE.

TELEPHONE-EXCHANGE APPARATUS.

SPECIFICATION forming part of Letters Patent No. 442,144, dated December 9, 1890.

Application filed November 23, 1888. Serial No. 291,658. (No model.)

To all whom it may concern:

Be it known that I, CHARLES E. SCRIBNEP., a citizen of the United States, residing at Chicago, in the county of Cool; and State of Illinois, have invented a certain new and useful Improvement in Telephone-Exchange Apparatus, (Case 179,) of which the following is a it'ull, clear, concise, and exact description, reference being had to the accompanying drawio ings, forming a part of this specification.

My invention relates to telephone-exchange systems in which metallic circuits are einployed, and its object is to provide for uniting any two circuits together without including in the united circuit thus formed any electro-magnetic device or devices other than the telephones ofthe subscribers who are thus connected together, while at the same time means are provided for signaling between the zo central ofiice and the different subscribers for the connections and disconnections, as occasion may require.

My invention consists, first, in telephone lines, each consisting` of twolinibs or branches,

one limb ot each telephonelline being normally grounded at the subscribers station and open at. the central office, the other limb being normally open at the subscribers station and grounded at the central cil-ice through an annunciator and battery, a different annunciator being provided for each telephone-line, and the battery being preferably common to a large number ot lines 3 second, in metallic circuits, each limb being provided with a different terminal upon the switch-board, or in case of multiple switch-boards upon each of the switch-boards at the central oiiice, and double-stran ded cords provided with termin al plugs for uniting any two of saidl telephone 4o lines together, the plugs each being provided with two terminals adapted to close upon different terminals of the telephone-lines, respectively, the strands of said cords being re ciprocally connected from the terminal of one plug to the opposite terminal ot the other plug ot the pair; third, in a pair of connectingplugs, each provided with two terminals-as, for example, a metallic tip and a metallic sleeve upon the shank of the plug-said plugs 5o being connected together by flexible cords,

one strand extending from the tip of one plug tothe sleeve of the other, and the other strand connecting together the sleeve ofthe first and the tip of the second plug; fourth, in two telephone-lines, each consisting ot' two branches 55 connected through the subscribers telephones at the respective subscribers stations thereof, one limb of the telephone-line including an individual annunciator of high self-inductive capacity and ext-ending from said individual 6o annu nciator through a common battery to ground, and a connection between said telephonelines at the central ottice reciprocally uniting the branches,which are normally open, of the twolines, respectively,with the branches 6 5 which are permanently grounded at the central office, whereby the two telephone-lines are united in metallic circuit and provided with a branch connection through a different selfinduction coil on opposite sides of said metallic 7c circuit; and fifth, in providing a condenser in one of the strands ot' the connecting-cords, a condenser in the operators telephone-eir cuit, and a high-resistance ground tcst-circuit including one coil of an induction-coil, the other coil of the induction-coil including the operators telephone, as hereinatterdescribed.

In the accompanying drawings, which are illustrative of my invention, Figure l is a view illustrative of three telephone-lines extend- So ing from the subscribers stations thereon to the central office, each telephone-line consisting of two branches, one branch of each being connected with a different portion or terminal of a socket on each of the three different switch-boards, and the other limb being connected through the other side or portion of each of said sockets and extending thence through an individual annunciator to a common ground-line, including a battery, to- 9o gether with the operators apparatus at two of the switch-boards. Fig. i? isa detailed view of a pair of loop-plugs having their opposite terminals reciprocally connected together. Fig. 3 is a detailed longitudinal section of the 95 preferable form of socket. Fig. 4 is a detailed view of a modified form of loop-plug. Fig. 5 is an end elevation of the loop-plug shown in Fig. 4.. Fig. 6 is a detailed sectional view of a modification of the lineterminals, roo

the socket being divided horizontally and adapted tol receive a plug of the formilllustrated in Figs. 4 and 5.

Like parts are indicated by similar let-ters and figures of reference throughoutthe different figures. t Referring to Fig. l, subscribers station l is connected with the switch-boards l, 2, and 3 at the central office by a metallic circuit a., consistingof two branches a and a2. The normal circuit of branch a may be traced from ground at subscribers station l, through the bell at said stat-iemand thence to the central oiii'ce. The normal circuit of the branch a2 may be traced from the normally-open grounding-key a3 at station l to the central office. At the central office each branch is provided on each of the switch-boards with a different terminal, the corresponding' termi nals otl the two branches on each board being, preferably, different insulated parts of the same socket. Thusthel sockets c (l of the line a on each of the boards consist each ot' two parts-that is to say, socket l) consists of the insulated parts o b2, socket c consists of the insulated parts c c2, while4 socket d consists of the insulated part-s d d2. Branch a is connected with the portions Zic d", while branch a2 is connected with the portions 19202 d2. The branch a is normally open at the central office, while the other branch a2 eX- ten'ds through an individual annunciator e, constructed to act also as a self-induction coil, and thence to wire f toground, a battery g being included in the ground-wire f. Subscribers station 2'is connected in the same manner with the switchsboards l 2 3 by the line 71 branch- 7L ot' said lineI being normally grounded at sta-tion 2 and normally open at th-e central office, while' branch Wis normally open at station 2Y and normally grounded through an individual annunciator t', connected with the ground-wire f through batteryV g.

Station 3, it will be understood, is provided with subscribers apparatus similar to thev apparatus' shown at stations I and 2, is connected in the same manner by wire 7c with the central-office apparatus, branch 7c being normal-ly open and branch k2' being connected through individual annunciator l, and thence to the wire'f, which includes the common battery g, as shown. As shown in Fig. 2, m is the answering loop plug, consisting of two insulated parts or' terminals mng. The other plug n, which may be termed thel connecting plug is provided with two in Y sulated parts or terminals nn2. It will beobserved that the strand o connects terminalm of plug m with terminal n2 of plug/1t, while strand o connects terminal at of plug n with terminal m2 of plug m-that is to say, the-opposite terminals of the pair of plugs are reciprocally connected together. In the strand o is placed a condenser 1J and the `usual calling-key p', the condenser being nearest to' the plug n. The connections 292193 terminal el".

from the different strands o o', respectively,

extend to the operators telephone contact# be provided at each ot' the boards, as shown at board l, Fig. l.

l will now describe the operation ol my apparatus. We will suppose subscriber at station 2 desires a connection with the subscriber at station l. S'ubscri'berat station 2, by pressing onv his key qat station 2 closes the branch h2 to ground, and thus current from battery g* is sent through an'nunciator t'. rPhe operator at board 3, seeing shutter yi fall,

. inserts heranswering-plu'g'm, as shown in the switch or socket of line h upon board 3, and

jthe subscriber takes down his telephone.

The ground-connection of branch 71, at station 2 is thus taken off and the telephone looped into the line h in metallic circuit. As soon as the telephone is thus taken down the circuit of battery g is connected over branch h2 through station 21o branch 7L', and hence tothe terminals of the different sockets'with which saidA branch 7L is connected. The test consists i-n determining the presence or absence of battery at any of the said terminals in the manner hereinafter explained or otherwise. rlhe operatorat the same time throws down the cam-lever Q4 of herlistening-in key, thus looping her telephone Yinto the circuit. The operator is thus brought into connection with'subscri-ber of station 2 and receives the order. She next proceeds to test the l'ine` called for. This test is made by touching the point of the test-plug q' to the outer portion d of the socket dthat is ton say', the portion of the socket connected with-the branch a," of the telephone-line,whatever may be the particular form of the sockets or the position of the different terminals thereof. ['f the telephone at station' l is on the telephone-switch and the line is not connected with any other line,v no current from battery g will beV found present when the tip of test-plugq is applied tothe lt, however, the telephone removed froln thel telephone-switch, or if the line has been called for and connected by a connecting-plug with any other line upon either'of: the boards, current from batteryV gv will be sent through the test-plug q and the induction-coil q', andthe telephone of the op' erator being inclu-ded" in the circuit of thez other coil ot' the induction-coil qi. The operator, listening and' hearing the son nd caused by the induced currents,` will know that the line is in use. If the lin-e thus tested has been connected with another line by'means of the connecting-plug n, battery will be present at the test-pieces b', c', the., without regard to the position of the subscribers telephone. Thus, as shown at board ll,testplug r is shown applied to the test-piece b of switch Z) of line o, and the telephone at station l. of line d is on the hook. The linewill, however, test busy 7 since the battery g will be found connected with said terminal or test.- piece b. The circuit may be traced as follows: YFrom battery g by wire f and branch h2 to the terminal m2 of answering-plug fm, and thence by strand o to the terminal n of plug n, which terminal 71, is in contact with the test-piece d of plug d, and thence over the branch d to test-piece b' of switch Z1. The resistance r, included in circuit with the testplug, should be such that the current from battery g, thus closed through the test-plug, will not be sut'tieient to throw down the shutter i when the test-plug is thus made. The object of the condenser p is to prevent the annunciator of the called subscriber from being thrown down when the subscribers are through talking and hang up their telephones. The condenser p4 has the same function in case the operator should be listening in at the time the calling subscriber hangs up his telephone. 'hen the subscriber called hangs up his telephone, the calling subscribers individual annunciator is thrown down, thus notifying the operator to disconnect. Thus suppose subscriber at station l hangs up his telephone, as shown, while the lines uy and 7L are connected, as shown at board 3. The subscriber at station l in this instance would be the called or answering subscriber, and the subscriber of station 2 would be the calling subscriber. The telephone of the answering subscriber at station l being hung up, branch d is connected to ground at station 1, and thence to terminal 7/ ot' the socket d, and thence to terminal n-of plug n, and thence to the tip m2 of plug n, and thence by wire h2 through the annunciator i, and thence to wire f, and through battery gto ground. Annunciator t' of the calling subscriberis thus thrown down when the answering subscriber hangs up his telephone. Then the calling subscriber hangs up his telephone, as shown at station 2, current from battery g will not be sent through individual annunciator e of the answering' subscriber, since the condenser p will be found included in the circuit. The circuit formed through the condenser p angl annunciator e may be traced from ground at station 2 over branch 7L to terminal in' of the plugm, and thence over strand o to condenser p, and thence to the tip n2 of plug n, and thence over a portion of branch wire o? through the answering subscribers annunciator e, and thence through batteryg to ground. The annunciatorewill not be operated, therefore, when the calling subscriber hangs up his telephone. In case the operators telephone were connected into the circuit, still the condenser p* would prevent battery current-from battery y from [lowing through annunciator c.

It is well known in the art that a Condenser in a telephone-circuit is not objectionable. 'lhough the line is thus made open as to ordinary battery-currents, still the circuit is complete as to voice currents-that is to say, the two connected subscribers can telephone over a circuit including a condenser the same as if the condenser were not present'.

I have described my invention as applied to a multiple-switch -board telephoneexchange system. Certain features thereof,how ever, it is evident, might be employed to ad vantage in single switch-board systems. As shown in Figs. e and 5, the loop-plng has its two terminals on opposite sides thereof, these terminals being insulated by suitable insulating material. The socket shown in Fig. (i is divided longitudinally instead of transversely, as shown in Fig. This plug-socket, Fig. G, is especially designed to receive a loopplug of the form shown in Figs. 4 and 5.

My invention as t-hus described admits of various modifications, which would readily suggest themselves to those skilled in the art, and I therefore do notI limit myself to the constructions shown.

Having thus described my invention, I ela-im as new and desire to secure by Letters Patent-- 1. A metallic telephone-line circuit con sisting of two branches, one branch being normally connected with ground at the subscribers station, and thence through the sub scribers bell to the telephone switch, and thence to the central ofce, said branch being connected with the test portion of a socket on each of two or more switch-boards and being normally open, while the othcrbranch, being normally open at the subscribers station, extends to the other terminals of the same sockets on said switch-boards, and thence through an annunciator and a battery to ground, in combination with the telephone switch and a ground-keyat the snbscribers station, whereby on depressing the grounding-key current from the battery is sent through the individual annunciator, while on operating the telephone-switch the two branches are united in metallic circuit.

2. A pair ot loop-plugs and connectingcords, the strands ot' said cords being connected, respectively, from one terminal of one of the plugs to the opposite terminal of the other plug reciprocally, in combination with a condenser included in one of said strands, substantially as and for the purpose sp eciied.

Two metallic circuit telephone -lines looped together at the central station, each of saidlines being provided with a ground branch through its individual annunciator and a battery to ground, the looping device consisting of a pair of plugs, cach having two terminals and different strands, each of the terminals of one plug being connected with the opposite terminals, respectively, of the other plug,

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and a condenser included in the circuit between two ot' said opposite terminals, substantially @sand for the purpose specified.

4.' Two telephone-lines, each consisting of two branches, one branch of each being normally grounded at the central otce through an annunciator and battery and the other branch of each bei-ng normally open, a looping device connecting reciprocally the normally-open branches with the closed branch es, and acondenserincluded between two of said connected terminals and switching'a-pparatus at the different subscribers stations operated by vthe telephones, whereby on hanging up the telephone of one station the annunciator of the line is operated as a clearing-out signal, whileI on hanging up the telephone ot the other station the current is prevented from flowing through the annunciator of the line of the irst station, substantially as and for the purpose specified.

5. The combination, with the telephoneline extending from ground at the central office through a battery to terminals, one on each switch-board, and then-ce to the subscribers station and thence back to' test-terminals, one on each switch-board, of switching apparatus at the subscribers station for forming a ground connection for the battery or uniting thetelephone-line-throu gh the-subscribers station in metallic circuit to connect the battery to the said test-terminals. Y

G. The combination, with the telephoneline extending from ground at thev central ofce through a battery to terminals, one on each switch-board, and thenceV to thev subscribers station, and thence back to test-terminals, one on each switch-board, of switching apparatus at the Subscribers station for forming a ground connection for the battery or ul'iiting the telephone-line through the subscribers station i'n -rn etall'i'c circuit. to connect the battery to the said test-terminals, and

testing apparatus for determining the presence or absence of battery-current at saidl testterminals at thev dittcrent boards to determ ine whether the line is in use.

7. The combination, with a pair ot' loopplugs having different terminals reciprocally l connected together by different strands or wiresv diagonally or oppositely, of a condenser included in one of said strands, and a telephone in a bridge between the cords, a condenser beingincluded, also, in the bridge, substantially as and for the purpose specified.

S. The combination, with pair of loopplugs having different terminals reciprocally connected together by different strands or wires diagonally or oppositely, ot' a condenser included in one of said strands and a telephone in a bridge between the cords, a condenser being included, also, in the bridge, a converter having one coil including the said telephone and the other coil including ay branch ground-circuit of high resistance provided with a test-plug or movable terminal adapted to close upon any one of several testpieces provided upon a telephone switchboard. Y

9. Two telephone-lines a and h, each consisting of two branches, branches a andvh ofthe said lines being each normally grounded through the bell of its subscribers station and each extend-ing to different test-terminals, one for each line on each board, the branches a2 and h2 beingeach permanently grounded at the central oiice and eacliextending through a battery and a different individual annunciator and to different terminals, one tor each of said branches a2 h2' on each board, the test piece and terminal of each line on each board form-ing a divided socket adapted to receive a loop-plug, said" branches continuing to a normally-open grounding-'key at the respective subscribers stations thereof, the telephone and telephone-switch at each subscribers station, and operators calling, testing, and con- -necti'ng apparatus at the ditt'erent boards, whereby the lines mav be united for conversation at one board and tests made at any of the other boards, substantially as and for the purpose' specified.

In witn ess whereof I hereunto subscribe my name this l Tth'd-ay of November, A.D. 1888'.

` CHARLES E. SCRBNER'. 1Witnesses GEORGE P. BARTON, ELLA EDLRR. 

